Business Sri Lanka recommends carrying some cash for smaller purchasing and spending in Sri Lanka, including payments for taxi trips. However for the majority of your spending, all the major internation credit cards are generally accepted. It is not necessary to buy currency in advance as there is a cash machine and banks located in the arrivals areas of the airport. The government regulates currency transactions and you will find the rates fair and consistent between the various banks.

Getting from the airport to Colombo costs a maximum GBP 20 or Euro 30. It is advisable to use the taxi booking service inside the arrivals hall and ensure you are booking an air conditioned taxi. Most of the taxi are a minibus so do consider sharing a taxi with fellow travellers. 

Keep a number of smaller denomination notes (Rs.50 and Rs.100 notes for tipping (which is generally expected).

Cash machines are commonplace throughout Colombo and in most towns in Sri Lanka. Many of the better hotels have cash machines.

HSBC branches are common and their machines will accept all European bank cards. A list of banks in Sri Lanka along with links to their websites can be found on this page.